The report by M A Weber and colleagues (May 31, p 1848) supports many previous studies in which Staphylococcus aureus and gram negative organisms were isolated from infants who died suddenly and unexpectedly. S aureus best fits predictions of the bacterial toxin hypothesis of sudden unexpected death in infancy. There are research groups with specialist techniques for detection of various bacterial toxins and the host’s response to them; co-operative studies between these groups with clinical teams such as that at Great Ormond Street could provide significant insights into the role of infectious agents and inflammation in SUDI.